Our research efforts will center on the we of a variety of mathematical techniques to solve and analyze the complex differential equations which arise in the modeling of systems in biology, ecology and physiology. Particular systems of interest include: *the renal concentrating mechanism *biochemical oscillators *reaction-advection processes *long-term fluctuations of populations *nonlinear models of the DNA molecule Exact, approximate and numerical solutions will be obtained. The mathematical techniques to be used include perturbation (both regular and singular) and asymptotic series, harmonic balance procedures, phase-space analysis, the "theory" of chaotic systems, and numerical integration.